Micro-emulsions are transparent or translucent systems consisting of two immiscible liquids, one being dispersed in the other. The dispersed, discontinuous, or internal phase is the liquid that is broken up into droplets of less than about 2000 Angstroms. The surrounding liquid is known as the continuous or external phase.
Aqueous based lubricants and functional fluids have been greatly in demand not only because of their low cost, but also because of their ease of disposal, reduced dependence on supply of petroleum-derived base fluid, and their fire resistance.
Antiwear compounds are well known in the art for their use in conventional oil-based lubricants. For example, numerous metal-based additives are disclosed in the book "Metal-Based Lubricant Compositions", by Henry M. Drew, Noyes Data Corporation, Chemical Technology Review No. 48 (1975).